Generally, a coupling is directed to transferring a driving force between a prime mover and a driven device and to performing a driving force transfer while protecting both shafts even when there is displacement (eccentricity, declination, axial movement displacement) between a shaft of a prime mover and a shaft of a driven device.
When an over load occurs at either a driven device or a prime mover, since an over load is directly transferred, it might damage a driven device or a prime mover. In order to prevent such damages, a coupling is being improved.
Korean utility model publication number 20-2000-0006952 discloses a coupling unit which comprises a power lock assembly disposed at the inner diameter parts of first and second flanges installed at two different shafts and fixed at the shafts with transfer torques defined by means of the first and second flanges coming into contact with a circumferential surrounding portion with the aid of a surface pressure, a friction plate and a bushing which are disposed between the first and second flanges, and a bolt and a nut which connect the first and second flanges by way of the friction plate and the bushing, by means of which construction the displacement and declination in an axial direction can be compensated, and when a force exceeding a set transfer torque is transferred to the shaft, the shaft slips at the power lock assembly, thus offsetting the torque exceeding a set level as the shaft slips at the power lock assembly when the force exceeding a set transfer torque is transferred to the shaft, thus consequently preventing the shaft and other elements from damages.
Korean patent publication number 10-1998-0001744 discloses an electrically insulated coupling which comprises an outer hub in which there are provided two facing coupling members connecting two rotating shafts and disposed at each shaft, and an inner hub is coupled to each shaft in at least one coupling member between the two coupling members, with the outer hub being mounted at the concentric shaft of the inner hub and being connected with the opposite coupling member, an electrically insulated part disposed between the contact surfaces between the inner and outer hubs for thereby electrically insulating the hubs, and a second hollow key disposed a contract surface between the inner and outer hubs in an electrical insulation way.